In many disturbances of the volitional motor patterning due to spinal cord lesion, the patient experiences a combination of loss of discrete control over muscles and muscle groups, interference of willed motor actions by concomitant involuntary muscle activity and "spontaneous" involuntary contractions such as "spasms" and "tremors." A new experimental approach is proposed to quantitatively assess the extent and type of involuntary motor activity in spinal cord injury. It uses long-term ambulatory tape recordings of the electromyographic activity of selected muscle groups, combined with rapid off-line analysis of the resultant recordings. It is hypothesized that by the development of criteria and measures, based on the analysis, it is possible to (1) determine the efficacy of spasm treatment in a functionally meaingful manner, (2) document characteristic trends in the patterns of involuntary motor activity, and (3) assess, to some extent, the degree of interference with specific willed motor functions. All three of the above are of clinical importance. Classification of involuntary motor patterning is a relevant approach to a number of fundamental questions about the neutral organization of normal motor control. The proposed experimental approach may be applicable to other neurological lesions that cause comparable motor disability and symptoms.